Other Liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Other liabilities
Employee compensation and benefits	$ 19,789	$ 18,356
Liability for pension benefits	231,424	232,788
Liabilities for uncertain tax positions	2,517	2,416
Other	15,906	20,393
Other liabilities (less current portion)	$ 269,636	$ 273,953